Production of alkaline-earth titanates



Patented May 27, 1930 UNITED STATES PATENT OFF-ICE REGINALD HILL MONKAND LUDVIG FIRING, OF MONTREAL, QUEBEC, CANADA; SAID FIRING ASSIGNOR TOJOHN IRWIN, OF MONTREAL, CANADA PRODUCTION OF ALKALINE-EARTH TITANATESNo Drawing.

This invention relates to pure alkali-earth metal titanates suitable foruse as'pigments as well as for other technical purposes, and to aprocess of producing such titanates.

In the production ofpigments, it has heretofore been proposed toincorporate titanates in composite titanium pigments. By the methodspreviously suggested, an alkaliearth metal carbonate is added to atitanium hydrate containing SO whereby an insoluble sulphate and atitanate of the alkaline earth are formed, and these with the tianiumoxide form the composite pigment. Such a composite pigment may have,inherently, different indices of refraction which influence the opacityof the pigment.

The object of this invention is to produce pure alkali-earth metaltitanates, which are well adapted for various technical uses, and whichare excellent paint pigments. These titanates are substantially freefrom all foreign matter and are not composite products.

The hydrates of titanium, the raw material to which the process of thisinvention is applied, produced by the now well known methods, usuallycontain S0 lVe have found the presence of this $0., in the form in whichit exists in the titanium hydrate, detrimental to the formation oftitanates, and therefore an essential step in the complete process ofthis invention is the removal of the S0 It will be apparent that if 80.is not removed from the raw material, the final product will containundesired compounds.

For use as a pigment,'the product should be free from grit or hardparticles and have a soft texture.

In accordance with this invention, an aqueous paste of freshlyprecipitated titanium hydrate, substantially free from impurity, istreated to remove all the SO, without leaving any insoluble salt of thisacid radical. To this so treated titanium hydrate, a sulficient quantityof an aqueous paste of carbonates of the alkali-earth metals is added,so that the final product obtained contains a predetermined quantity ofTiO,;. It has heretofore been recognized that the tinctorial capacity ofa titanium pigment has a dehnlte Application filed February 10, 1927.Serial No. 167,354.

relation to the TiO content of the pigment.

In order to hasten the completion of the reaction and facilitate theproduction of a final product of pure white colour, soft in texture andfree from grit or hard particles, there is added to the mixture of thetitanium hydrate and carbonate, a substance which acts as an acceleratorfor the reaction. For this purpose,-hydrochloric acid or the equivalentsalt, such as barium chloride, may be used. It is thus possible togreatly reduce the time required for the completion of the reaction,approximately one-half an hour, after the mixture reaches the requiredtemperature, being sufficient for the formation of the titanatcs.Furthermore, the temperature employed may be from 200 to 300 C. lowerthan that necessary in the operation of the direct process or if the S0is not completely removed from the hydrate. Thevhigh tempcratureordinarily required is detrimental in securing the character of productdesired in that it tends to produce a hard, unsatisfactory pigment.

To illustrate a specific embodiment of the invention and describe aparticular application thereof, the following example is given.

' To an aqueous paste of freshly precipitated titanic acid a sufficientquantity of a normal acetate, such as zinc acetate, sodium acetate orammonium acetate, is added to react with the SO. present. The sulphatethus formed is entirely eliminated by washing with water. To the pastethus prepared is added a sufficient quantity of barium carbonate inpaste form to produce a compound having the formula BaTiOg. For thisreaction, titanic acid, equivalent to 100 parts TiO requiresapproximately 248 parts of dry barium carbonate. chloric acid are addedto this mixture which is then fed into a furnace, the temperature ofwhich is raised to approximately 750 to 880 (1., depending upon theproperties desired in the final product. .For the production of thetitanatefor use as a pigment, a temperature of 830 C. gives goodresults.

When the reaction is complete, the product is of a purewhite colour,free from sulphates Approximately 3 part-s of hydroalkali-earth metal.

or other impurities and in a fine state of division. It has a faintalkaline reaction.

In neutralizing the S0 in the titanic acid, it is found thatwhen'alkaline or basic materials are used, a portion of such material isabsorbed by the titanic acid, forming comble salts be formed so thatthey may be entirely removed by washing.

It will be apparent that the product is formed at a temperature lowerthan that at which the titanates of the alkali-earth metals are usuallyformed. When the product is to 'be used for other than pigmentarypurposes,

the higher temperatures may give satlsfactory results, but in order tosecure in the product the best covering capacity, temperature controlis. essential.-

While a detailed description has been given for a clear understanding ofthe invention, it is to be understood that the following claims are tobe interpreted as broadly as permissible in View of the prior art.

What we claim is: v 1. In a'prooess of producing alkali-earth metaltitanates from pure titanium hydrates and alkaline earth carbonates, thestep which consists in treating the mixture, at a temperaturesubstantially lowerthan that atvwhich such titanates are usually formed,in the presence of a small quantity of chloride of an 2. A process ofproducing alkali-earth metal titanate from precipitated titanium hydratecontaining S0 which comprises eliminating the S from the hydrate bytreatment with normal acetate of alkalimetal I or ammonium and washingwith water, addtanium hydrate which comprises completely eliminatingundesired acid substance from the hydrate by treatment with sodiumacetate and washing with water, adding 'to the hydrate the carbonate ofan alkali-earth metal and heating the mixture to form an alkaliearthmetaltita'nate.

washing with water.

perature between 750 and 880 C., substantially as herein described.

25. A process of producing a titanate of barium from precipitatedtitanium hydrate which comprises treating the hydrate with sodiumacetate to unite with all the S0 in the said hydrate, washing with waterto remove the sodium sulphate formed adding to the hydrate bariumcarbonate and adding a suflicient amount of HGl to form an acccleratorand heating the mixture to approximately 830 (3., as herein described.

6. The process of treating precipitated titanium hydrates containingundesired acid substance, whereby such undesired acid sub stance isremoved, which comprises treating the titanium hydrate with a normalacetate of an alkali metal or ammonium which, on

reacting, forms a water-soluble salt which is entirely eliminated bywashing with water, and Washing the mixture.

7 Ina process of treating precipitated titanium hydrates containing anundesired acid radical, the step which consists in entirely eliminatingthe undesired acid radical by treating the hydrate with a normalacetateof an alkali metal or ammonium and 8. The process of treatingrecipitated titanium hydrate containing S8 which comprises treating saidh drate with sufiicient sodium acetate to com ine with all the S0, toform soluble sodium sulphate and washing the mixture to entirelyeliminate the sodium sulphate. 7 v

'9. In the production of alkali earth metal titanates, the rocess whichcomprises eliminating any S 4 that may exist therein from with a normalacetate of an alkali metal or ammonium and washing with water, adding tothe hydrate an alkaline earth carbonate and a sufiicient amount of HClto form an accelerator and heatin the mixture.

In testimony whereo we have aflixed our signatures. 1

REGINALD. HILL MONK. LUDVIG FIRING.

precipitated'titanium hydrate, by treatment 4. In the production ofalkali-earth metal carbonate and sufiicient H01 to form \an S0,, addingto the purified hydrate barium acoelerator'and heating the to a tam-1

